Add pcbBoardCenter to allow specifying the center of the board

[seveibar]

This has no effect on the inner elements, it just changes how the edges are drawn.

[homie-gg]

Here are some pull requests that might be helpful reference for this task:

• accept pcbX and pcbY for
• handle pcb routes when finding center of bounds, handle no available points in bounds
• added pcb_board outline prop type